2,091 research outputs found
Model Checking Spatial Logics for Closure Spaces
Spatial aspects of computation are becoming increasingly relevant in Computer
Science, especially in the field of collective adaptive systems and when
dealing with systems distributed in physical space. Traditional formal
verification techniques are well suited to analyse the temporal evolution of
programs; however, properties of space are typically not taken into account
explicitly. We present a topology-based approach to formal verification of
spatial properties depending upon physical space. We define an appropriate
logic, stemming from the tradition of topological interpretations of modal
logics, dating back to earlier logicians such as Tarski, where modalities
describe neighbourhood. We lift the topological definitions to the more general
setting of closure spaces, also encompassing discrete, graph-based structures.
We extend the framework with a spatial surrounded operator, a propagation
operator and with some collective operators. The latter are interpreted over
arbitrary sets of points instead of individual points in space. We define
efficient model checking procedures, both for the individual and the collective
spatial fragments of the logic and provide a proof-of-concept tool
Distance Closures on Complex Networks
To expand the toolbox available to network science, we study the isomorphism
between distance and Fuzzy (proximity or strength) graphs. Distinct transitive
closures in Fuzzy graphs lead to closures of their isomorphic distance graphs
with widely different structural properties. For instance, the All Pairs
Shortest Paths (APSP) problem, based on the Dijkstra algorithm, is equivalent
to a metric closure, which is only one of the possible ways to calculate
shortest paths. Understanding and mapping this isomorphism is necessary to
analyse models of complex networks based on weighted graphs. Any conclusions
derived from such models should take into account the distortions imposed on
graph topology when converting proximity/strength into distance graphs, to
subsequently compute path length and shortest path measures. We characterise
the isomorphism using the max-min and Dombi disjunction/conjunction pairs. This
allows us to: (1) study alternative distance closures, such as those based on
diffusion, metric, and ultra-metric distances; (2) identify the operators
closest to the metric closure of distance graphs (the APSP), but which are
logically consistent; and (3) propose a simple method to compute alternative
distance closures using existing algorithms for the APSP. In particular, we
show that a specific diffusion distance is promising for community detection in
complex networks, and is based on desirable axioms for logical inference or
approximate reasoning on networks; it also provides a simple algebraic means to
compute diffusion processes on networks. Based on these results, we argue that
choosing different distance closures can lead to different conclusions about
indirect associations on network data, as well as the structure of complex
networks, and are thus important to consider
Quotient on some Generalizations of topological group
في هذا البحث ، تم تعريف بعض التعميمات للمجموعة التبولوجية وهي المجموعة التبولوجية - α ، والمجموعة التبولوجية - ب ، والمجموعة التبولوجية - β مع أمثلة توضيحية. بالإضافة إلى ذلك ، تم تعريف المجموعة التبولوجية للشواء فيما يتعلق بالشواية. فيما بعد ، تم تداول حاصل قسمة تعميمات المجموعة التبولوجية في مجموعة تبولوجية - p معينة. علاوة على ذلك ، تمت مناقشة نموذج النظام الروبوتي الذي يعتمد على حاصل المجموعة التبولوجية – p.In this paper, we define some generalizations of topological group namely -topological group, -topological group and -topological group with illustrative examples. Also, we define grill topological group with respect to a grill. Later, we deliberate the quotient on generalizations of topological group in particular -topological group. Moreover, we model a robotic system which relays on the quotient of -topological group
06341 Abstracts Collection -- Computational Structures for Modelling Space, Time and Causality
From 20.08.06 to 25.08.06, the Dagstuhl Seminar 06341 ``Computational Structures for Modelling Space, Time and Causality\u27\u27 was held in the International Conference and Research Center (IBFI), Schloss Dagstuhl.
During the seminar, several participants presented their current
research, and ongoing work and open problems were discussed. Abstracts of
the presentations given during the seminar as well as abstracts of
seminar results and ideas are put together in this paper. The first section
describes the seminar topics and goals in general.
Links to extended abstracts or full papers are provided, if available
On Quasi-Isometry of Threshold-Based Sampling
The problem of isometry for threshold-based sampling such as
integrate-and-fire (IF) or send-on-delta (SOD) is addressed. While for uniform
sampling the Parseval theorem provides isometry and makes the Euclidean metric
canonical, there is no analogy for threshold-based sampling. The relaxation of
the isometric postulate to quasi-isometry, however, allows the discovery of the
underlying metric structure of threshold-based sampling. This paper
characterizes this metric structure making Hermann Weyl's discrepancy measure
canonical for threshold-based sampling.Comment: submitted to IEEE Transactions on Signal Processin
Annotation Scaffolds for Object Modeling and Manipulation
We present and evaluate an approach for human-in-the-loop specification of
shape reconstruction with annotations for basic robot-object interactions. Our
method is based on the idea of model annotation: the addition of simple cues to
an underlying object model to specify shape and delineate a simple task. The
goal is to explore reducing the complexity of CAD-like interfaces so that
novice users can quickly recover an object's shape and describe a manipulation
task that is then carried out by a robot. The object modeling and interaction
annotation capabilities are tested with a user study and compared against
results obtained using existing approaches. The approach has been analyzed
using a variety of shape comparison, grasping, and manipulation metrics, and
tested with the PR2 robot platform, where it was shown to be successful.Comment: 31 pages, 46 Figure
Spatial Logics and Model Checking for Medical Imaging (Extended Version)
Recent research on spatial and spatio-temporal model checking provides novel
image analysis methodologies, rooted in logical methods for topological spaces.
Medical Imaging (MI) is a field where such methods show potential for
ground-breaking innovation. Our starting point is SLCS, the Spatial Logic for
Closure Spaces -- Closure Spaces being a generalisation of topological spaces,
covering also discrete space structures -- and topochecker, a model-checker for
SLCS (and extensions thereof). We introduce the logical language ImgQL ("Image
Query Language"). ImgQL extends SLCS with logical operators describing distance
and region similarity. The spatio-temporal model checker topochecker is
correspondingly enhanced with state-of-the-art algorithms, borrowed from
computational image processing, for efficient implementation of distancebased
operators, namely distance transforms. Similarity between regions is defined by
means of a statistical similarity operator, based on notions from statistical
texture analysis. We illustrate our approach by means of two examples of
analysis of Magnetic Resonance images: segmentation of glioblastoma and its
oedema, and segmentation of rectal carcinoma
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Using GPS technology to quantify human mobility, dynamic contacts and infectious disease dynamics in a resource-poor urban environment.
Empiric quantification of human mobility patterns is paramount for better urban planning, understanding social network structure and responding to infectious disease threats, especially in light of rapid growth in urbanization and globalization. This need is of particular relevance for developing countries, since they host the majority of the global urban population and are disproportionally affected by the burden of disease. We used Global Positioning System (GPS) data-loggers to track the fine-scale (within city) mobility patterns of 582 residents from two neighborhoods from the city of Iquitos, Peru. We used ∼2.3 million GPS data-points to quantify age-specific mobility parameters and dynamic co-location networks among all tracked individuals. Geographic space significantly affected human mobility, giving rise to highly local mobility kernels. Most (∼80%) movements occurred within 1 km of an individual's home. Potential hourly contacts among individuals were highly irregular and temporally unstructured. Only up to 38% of the tracked participants showed a regular and predictable mobility routine, a sharp contrast to the situation in the developed world. As a case study, we quantified the impact of spatially and temporally unstructured routines on the dynamics of transmission of an influenza-like pathogen within an Iquitos neighborhood. Temporally unstructured daily routines (e.g., not dominated by a single location, such as a workplace, where an individual repeatedly spent significant amount of time) increased an epidemic's final size and effective reproduction number by 20% in comparison to scenarios modeling temporally structured contacts. Our findings provide a mechanistic description of the basic rules that shape human mobility within a resource-poor urban center, and contribute to the understanding of the role of fine-scale patterns of individual movement and co-location in infectious disease dynamics. More generally, this study emphasizes the need for careful consideration of human social interactions when designing infectious disease mitigation strategies, particularly within resource-poor urban environments
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Dirac Triples for Unital AF Algebras
For a unital AF algebra A, we construct a family of triples (A, H, D) where A is represented faithfully on the Hilbert space H and D is an unbounded self-adjoint operator on H. These triples have the same properties as spectral triples except for the compact resolvent condition, so we call them Dirac triples. They serve as a generalization of Pearson-Bellissard spectral triples for an ultrametric Cantor set corresponding to choice functions. Pearson and Bellissard showed that the underlying ultrametric can be recovered by considering spectral triples associated to all choice functions. We obtain an analogue for unital AF algebras: the supremum of the Connes spectral distances induced by a large family of Dirac triples from our construction coincides with a generalized version of the Aguilar seminorm, which is a Leibniz Lip-norm for a unital AF algebra. Moreover, the convergence result of Aguilar is retained: equipped with the generalized Aguilar seminorm, a unital AF algebra is the limit of its defining finite-dimensional subalgebras for the quantum Gromov-Hausdorff propinquity
A digital analogue of the Jordan curve theorem
AbstractWe study certain closure operations on Z2, with the aim of showing that they can provide a suitable framework for solving problems of digital topology. The Khalimsky topology on Z2, which is commonly used as a basic structure in digital topology nowadays, can be obtained as a special case of the closure operations studied. By proving an analogy of the Jordan curve theorem for these closure operations, we show that they provide a convenient model of the real plane and can therefore be used for studying topological and geometric properties of digital images. We also discuss some advantages of the closure operations investigated over the Khalimsky topology
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